HUMAN SKIN - NUDE MOUSE MODEL. We have established a model for long-term cultivation of adult human skin on the nude athymic mouse. Psoriatic skin can be grown for periods of several months and retain the essential features of psoriasis. Epidermal kinetics studies confirm a hyperproliferative state in these grafts. Recombinant studies of normal and psoriatic epidermis and dermis have localized the site of the pathologic defect in psoriasis to both epidermis and dermis. Studies are also underway utilizing the human skin-nude mouse system to study conservation of regional epidermal specificities and the effect of non-dermal connective tissue on epidermal maintenance. Epidermal kinetic studies are also underway on normal adult human skin to measure the percentage of cycling cells (growth fraction). Formation and Function of Structures at the Epidermal-Dermal Junction in Normal and Diseased Human Skin. Studies are underway to selectively isolate components of the epidermal-dermal junction, particularly anchoring fibrils. Crude "anchoring fibril" enriched extracts have been obtained from human skin. A monoclonal antibody has been prepared that reacts with a normal human skin basement membrane antigen by immunofluorescent studies. On immunoelectronmicroscopy, monoclonal basement membrane zone antibody localized to the sub-basal lamina area, particularly associated with anchoring fibrils. Plans are to further document this association and to use this antibody as a tool to selectively isolate anchoring fibrils from crude "anchoring fibril enriched" preparations.